Guard assemblies

Abstract

An example system in accordance with an aspect of the present disclosure includes an opening assembly and a guard assembly installable in a floor above an enclosed region. The opening assembly is actuatable between an open configuration to provide access to the enclosed region, and a closed configuration in which the opening assembly provides a closed surface. A guard assembly is mounted to the opening assembly and actuatable independent of the opening assembly, between a retracted configuration flush with the closed surface of the opening assembly, and a deployed configuration to serve as a guard for the opening assembly.

What is claimed is: 
     
       1. A system comprising:
 a guard assembly actuatable between a retracted configuration and a deployed configuration to serve as a guard; 
 the guard assembly including a plurality of shafts bound on their upper ends by an upper guard support and bound on their lower ends by a lower guard support; and 
 a plurality of linear bearings to slidably engage the plurality of shafts of the guard assembly, and wherein at least one shaft of the plurality of shafts has a customized diameter profile comprising a non-constant diameter along a length of the at least one shaft; 
 the customized diameter profile comprising multiple discrete changes in diameter along the shaft length, between a full diameter corresponding to being gripped securely by the linear bearings, and a reduced diameter allowing for slop between a linear bearing and the at least one shaft. 
 
     
     
       2. The system of  claim 1 , further comprising a plurality of guard actuators to actuate the guard assembly. 
     
     
       3. The system of  claim 1 , wherein the guard assembly has a circular configuration and the plurality of guard actuators comprises four guard actuators evenly distributed around a circumference of the guard assembly. 
     
     
       4. The system of  claim 3 , wherein the plurality of guard actuators are set with a thread pitch that, when power is lost, friction lock the guard assembly in place resisting gravity. 
     
     
       5. The system of  claim 1 , further comprising at least one guard panel disposed between a given pair of the plurality of shafts to provide safety protection. 
     
     
       6. The system of  claim 1 , further comprising a plurality of guard springs coupled to the guard assembly to bias the guard assembly toward the deployed configuration and reduce an effective weight of the guard assembly. 
     
     
       7. The system of  claim 1 , the customized diameter profile comprising a single reduction in diameter at a shaft position beyond a section of the shaft that is gripped by linear bearings when the guard assembly is in the deployed configuration. 
     
     
       8. The system of  claim 1 , wherein a lower portion of the at least one shaft corresponds to a full diameter section that enables a secure non-slop grip by the plurality of linear bearings when the guard assembly is in the deployed configuration. 
     
     
       9. The system of  claim 1 , wherein an upper portion of the at least one shaft corresponds to a full diameter section that enables a secure non-slop grip by the plurality of linear bearings when the guard assembly is in the retracted configuration. 
     
     
       10. The system of  claim 1 , wherein the customized diameter profile tapers in diameter from a full diameter section to a reduced diameter section according to a parabolic curve to allow for smooth engagement of the linear bearings coming in contact with the full diameter section and the reduced diameter section of the at least one shaft. 
     
     
       11. The system of  claim 1 , wherein at least two of the plurality of linear bearings are positioned at a given one of the plurality of shafts, the at least two linear bearings being spaced apart from each other along the shaft according to a bearing spacing. 
     
     
       12. The system of  claim 11 , wherein the customized diameter profile of the at least one shaft includes a plurality of sections of the shaft having a full diameter to be gripped by the linear bearings in a non-slop grip, the plurality of sections of the shaft being spaced apart from each other along the shaft according to the bearing spacing with reduced portions between and beyond the full diameter plurality of sections. 
     
     
       13. The system of  claim 11 , wherein the customized diameter profile of the at least one shaft includes a section of the shaft having a full diameter to be gripped by one of the at least two linear bearings in a non-slop grip in the deployed configuration, a diameter of the at least one shaft tapering to a reduced diameter beyond the section to enable a remaining one of the at least two linear bearings to grip the shaft with a slop grip in the deployed configuration. 
     
     
       14. The system of  claim 1 , wherein the plurality of linear bearings include linear bearing float features to allow the plurality of linear bearings to accommodate approximately a half-degree deflection in either direction, allowing the linear bearing to align itself to deflections of the guard assembly. 
     
     
       15. The system of  claim 1 , wherein the plurality of shafts include a plurality of different diameter profiles distributed across multiple different shafts. 
     
     
       16. The system of  claim 15 , wherein even-numbered shafts have a first diameter profile, and odd-numbered shafts have a second diameter profiles. 
     
     
       17. The system of  claim 16 , wherein the first diameter profile corresponds to straight shafts having constant full diameters along their entire lengths, and wherein the second diameter profile corresponds to each shaft having at least one full diameter portion and at least one reduced diameter portion. 
     
     
       18. The system of  claim 1 , wherein the customized diameter profile comprises more than one discrete change in diameter along the shaft length, the discrete changes being separated from each other along the shaft length. 
     
     
       19. The system of  claim 1 , wherein the guard assembly has a stroke length of 42 inches, to enable the deployed configuration to extend the plurality of shafts and the upper guard support 42 inches.